This one (rated Hard) was a relative doddle using Mandatory Pairs.
Quite a lot of 'Mutual Reception' cases arose and these assisted
greatly with the "Counting" of rows, columns and regions.

My solution started (as always) with a number of straightforward
allocations, then inspection by digit (1-9 in turn looking at all the
nuances of row, column and region interaction). At that point, I
usually have a look at what 'counting' can reveal. In this case
it revealed a lot and much progress was made - so much that
there was no need even to compile the 'Missing' profiles.

Solution time was less than half an hour.
Nov 29 was also rated 'Hard' - but what a difference!

Again, this one would have potential for anyone wishing to explore
the application of Mandatory Pairs as a technique.

Again, this puzzle leads me to question the soundness of the algorithm that is calculating difficulty. This one had 3 steps that required more than just seeing that a number had only one possible location in a row/column/group. As it only had one type of 'advanced' (kind of) technique required, I would have to say this is a 'medium' puzzle. But that's just my opinion.

Does anyone have a list of techniques used in solving Sudoku's? Are there standard terms used to define them?

Does anyone have a list of techniques used in solving Sudoku's? Are there standard terms used to define them?

You can find a good introduction to Sudoku techniques at the SadMan Software site.

Terminology is not completely standardized, but terms like "X-Wing," "XY-Wing," and "Swordfish" are widely recognized. One of the users on this site, someone_somewhere, has recently cooked up a new technique that he calls a "Constellation" -- you can read about that here and also over here. dcb